It is well known to treat textile yarns and fibers of synthetic material such as nylon and polyester in order to change their properties to be closer to those of natural fibers such as wool and cotton. These natural fibers are characterized by inherent crimp and short fibers which impart bulk, pleasant hand, the ability to breathe, insulating properties, good moisture absorption and other desirable properties.
In U.S. Pat. No. 3,345,718 there is disclosed a process for texturing fibrous textile material in which the material is fed in a substantially tensionless state between a set of opposed pressure surfaces having a meshing system of grooves which deform the fibrous material into a crimped, zigzag configuration in which the fibrous material is twisted in alternate directions in the regions of the apices of the crimps. When synthetic fibrous materials are treated by the process of this patent the resulting crimping makes the properties of the product more like those of natural fiber products. However, there are still substantial differences between such synthetic fiber products and textile products of natural fibers.